xtabond2 inv ifi gdpcap edu polrisk period*, gmm(edu l.gdpcap l.ifi, lag(1 2) coll) iv(polrisk period*) robust noconstant
xtabond2 inv ifi gdpcap edu cpi polrisk period*, gmm(l.edu l.gdpcap l.ifi l.cpi, lag(1 2) coll) iv(polrisk period*) robust noconstant
